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COGNITIVE PSYCHOLOGY BOOK NOTES!! Chapter 1: Intro to Cognitive Psychology cognition= the mental processes that are involved in perception, attention, memory, problem solving, reasoning, and decision making Cognitive psychology- the branch of psychology concerned with the scientific study of cognition The Challenge of Cognitive Psychology Although it is difficult to remember details or certain things, returning to the place where the memories were originally formed can reveal memories that were there all along The First Cognitive Psychologists Cognitive psychology research began in the 19th century before there was a field called cognitive psychology Franciscus Donders did one of the first cognitive psychology experiments Donders’ Reaction-Time Experiment: Donder’s conducted research on mental chronometry- measuring how long cognitive processes take; specifically, he was interested in how long it took for a person to make a decision; measured reaction time Reaction time= the interval between presentation of a stimulus and a person’s response to the stimulus one of the most widely used measures in cognitive psychology Donders had several reaction-time experiments that measured the reaction time to perceiving light: simple reaction time - reacting to the presence or absence of a single stimulus, as opposed to having to choose between a number of stimuli before making a response presenting stimulus (light) ( mental response (perceiving the light) ( behavioral response (pushing button) choice reaction time- reacting to one of two or more stimuli. For example, in Donders’ experiment, participants had to make one response to one stimulus, and a different response to another stimulus left light flashes ( “perceive left light” and “decide which button to push” ( press corresponding key Donders’ experiment is important because: it was one of the first cognitive psychology experiments it illustrates something extremely important about studying the mind – mental responses (perceiving light or deciding which button to push) cannot be measured directly, but must be inferred from the participants’ behavior **thus, we see that mental responses CANNOT be measured directly, but must be inferred from observing behavior Helmholtz’s Unconscious Inference: Helmholtz is another 19th century researcher who was concerned unconscious inference- Hemholtz’s idea that some of our perceptions are the result of unconscious assumptions that are made about the environment it occurs without any awareness or conscious effort Ebinghaus’s Memory Experiments learned lists of nonsense syllables like DAX, QEH, LUH, and ZIF he used nonsense syllables so that his memory would not be influenced by the meaning of a particular word Savings Method- method used to measure retentionin Ebbinghaus’s memory experiments. He read lists of nonsense syllables and determined how many repetitions it took to repeat the lists with no errors. He then repeated this procedure after various intervals following initial learning and compared the number of repetitions needed to achieve no errors. ex: if Ebinghaus had to repeat the list 9 times to initially learn it, it might only take 3 repetitions to relearn the list after a short interval Formula: savings = [(initial repetitions) – (relearning repetitions) ] / initial repetitions …then multiply by 100 to convert to percentage Savings = [ (9-3) / (9) ] x 100 = 67% Ebbinghaus was then able to plot the “forgetting curve,” which shows savings as a function of retention interval Ebbinghaus’ experiments were important because they provided a way to quantify memory and therefore place plot functions like the forgetting curve that describe the operation of the mind What do Ebbinghaus’ savings method and Donders’ reaction time method have in common? ( therdsy both measure BEHAVIOR to determine a property of the MIND The First Psychology Laboratories Donders, Helmholtz, and Ebbinghaus were usually based in departments of physiology, physics, or philosophy when studying the mind because there were no psychology departments at the time BUT… in 1879 Wilhelm Wundt founded the first laboratory of scientific psychology at the University of Leipzig, where he carried out reaction time experiments and measured basic properties of the senses, particularly vision and hearing structuralism- an approach to psychology that explained perception as the adding up of small elementary units called sensations basically, the overall experience is determined by combining basic elements of experience called sensations analytic introspection- a procedure used by early psychologists in which trained participants described their experiences and thought processes elicited by stimuli presented under controlled circumstances ex: Wundt asked participants to describe their experience of hearing a five note chord played on the piano, Wundt was interested in whether they heard the five notes as a single unit or if they were able to hear individual notes Table: Early cognitive psychologists Donders 1868 Experiment: Simple vs. choice reaction time Idea: Mental processes cannot be observed directly, but must be inferred from behavior Helmholtz 1860-80 Principle: unconscious inference Ebbinghaus 1885 Experiment: Memory for nonsense syllables Method: savings technique Result: forgetting curve Wundt 1879 Established the first laboratory of scientific psychology Theory: structuralism Method: analytic introspection The Decline and Rebirth of Cognitive Psychology The Rise of Behaviorism John Watson Founds Behaviorism- as a graduate student at the University of Chicago, Watson was not hapy with the method of analytic introspection since a) it produced extremely variable results from person to person, and b) the results were difficult to verify because they were interpreted in terms of invisible inner mental processes So, Watson proposed BEHAVIORISM- the approach to psychology which stated that observable behavior is the only valid data for psychology. A consequence of this idea is that consciousness and unobservable mental processes were considered not worthy of study by psychologists Watson rejects introspection as a method eliminates consciousness as topic for study suggests that psychology’s main topic for study should be behavior So basically, Watson’s goal was to eliminate the mind as a topic of study in psychology and to replace it with the study of directly observable behavior Watson’s famous “little Albert” experiment caused a 9 month old boy named Albert to become frightened of a rat by classically conditioning the rat with a loud noise Watson used the “little Albert” experiment to show that behavior can be analyzed without any reference to the mind SKINNER’s OPERANT CONDITIONING: B.F. Skinner’s approach would dominate psychology for decades to come; Skinner’s theory focused on how behavior is strengthened by positive reinforcers (food, social approval) and negative reinforcers (shock, social rejection) The Decline of Behaviorism Psychologists applied the techniques of conditioning to things like classroom teaching, treating psychological disorders, and testing the effects of drugs on animals. However, in 1950s changes occurred in psychology, eventually leading to the decline in the influence of behaviorism Noam Chomsky’s Critique of Skinner’s Verbal Behavior In Skinner’s book Verbal Behavior, Skinner explained the development of language in children in terms of operant conditioning and argued that they imitate speech that they hear, and repeat correct speech because it is rewarded BUT Chomsky says that language development is not determined by imitation or reinforcement, but by an inborn biological program that holds across cultures The Misbehavior of Organisms Another event that led people to question behaviorism was a paper called “The Misbehavior of Organisms” where Skinner’s students found that conditioning did not work on raccoons, rather, their behavior was moreso biologically programmed The Cognitive Revolution – a shift in psychology from the behaviorist’s stimulus-response relationships to an approach in which the main thrust was to explain behavior in terms of the MIND. one of the outcomes of the cognitive revolution was the introduction of the information-processing approach to studying the mind movement occurred in the 1950’s Information Processing Approach- the approach to psychology, developed beginning in the 1950’s, in which the mind is described as processing information through a sequence of stages One of the events that inspired psychologists to think of the mind in terms of information processing was a newly introduced information-processing device called the DIGITAL COMPUTER DIGITAL COMPUTER- the first digital computers, developed in the 1940s, were huge machines that took up entire buildings, but they slowly evolved into regular computers and even laptops; these computers were used to analyze data and suggest a new way to think about the mind. Cherry’s 1953 studies showed that PEOPLE ARE APLE TO FOCUS THEIR ATTENTION ON ONE MESSAGE AMONG MANY and THERE ARE LIMITS TO THE AMT OF INFORMATION THAT PEOPLE CAN DEAL WITH basically, a different message was whispered into each ear, but the person only remembered the one that they had to repeat Flow Diagram for an Early Computer: Input ( Input Processor ( Memory Unit ( Arithmetic Unit ( Output Broadbent’s Filter Model of Attention Input ( Filter ( Detector ( To memory basically, many messages enter a “filter” that selects the message to which the person is attending for further processing by a detector and then storage in memory. Applying this flow diagram to Cherry’s experiment, the input = sounds entering ears, the “filter” then lets trhough the part of the input to which the person is attending, and the “detector” records the information that gets through the filter Two Historic Conferences: Seminars and conferences is 1956 fueled the cognitive revolution but, don’t be fooled by the word “revolution” because it was more of an “evolution” that occurred over a long period of time First cognitive psychology book published in: 1967 How Do Cognitive Psychologists Study the Mind? Behavioral and Physiological Approaches to Cognition Behavioral Approach to the study of the mind- when the mind is studied by measuring a person’s behavior and by explaining this behavior in behavioral terms ex: Donders’ behavioral approach measured the relationship between the presentation of the light and the reaction time to respond to the light Physiological Approach to the study of the mind- when the mind is studied by measuring physiological and behavioral responses, and when behavior is explained in physiological terms UPDATED SEQUENCE OF EVENTS BETWEEN STIMULUS AND RESPONSE TAKES INTO ACCOUNT THE PHYSIOLOGICAL RESPONSE: stimulus ( physiological response(brain activated) ( mental response (perceive light, deciding) ( behavioral response The Behavioral Approach: Measuring Mental Rotation mental rotation = rotating an image of an object in the mind. Shepard and Metzler’s experiment provided evidence that people use this method when asked to determine whether 2 depictions are of the same object viewed from different angles or are 2 different objects - researchers found that it takes longer to compare 2 objects separated by a larger angle than 2 objects separated by a maller angle The Physiological Approach: The Relationship Between Brain Activity and Memory brain imaging technique enables researchers to identify which areas of the brain are activated as a person carries out a specific task Models in Cognitive Psychology models= a model in cognitive psychology is a representation of the workings of the mind. There are many different kinds of models, but many are represented as interconnected boxes that each represent the operation of specific mental functions. modal model of memory= the model proposed by Atkinson and Shiffrin describing memory as a mechanism that involves processing information through a series of stages, which include short and long term memory. It is called the modal model because of the great influence it has had on memory research MODAL MODEL: Input ( Sensory Memory ( Short term memory (-- rehearsal --) ( ( long term memory First stage = sensory memory: a brief stage of memory that holds information for seconds or fractions of a second. It is the first stage in the modal model of memory some of this information is then transferred into short-term memory- where information can be held for 15-20 seconds, unless it is rehearsed Although much information that enters short term memory is lost, some enters the long term memory where information can be stored for longer periods of time Something to Consider: Studying Cognition Across Many Disciplines cognitive science- the interdisciplinary approach to the study of the mind. Cognitive science includes a wide net of disciplines including computer science, linguistics, neuroscience, artificial intelligence, philosophy, and psychology. Psychology= cognitive psychologists focus on using behavioral measures to understand the operation of the mind and increasingly have taken a physiological approach as well. Computer Science= computer scientists are concerned with artificial intelligence – creating computer programs that can duplicate intelligent behaviors such as perceiving light and thinking Anthropology – cognitive anthropologists study the social and cognitive contexts of cognition. A cognitive anthropologist might, for example, study differences in thinking across different cultures Linguistics- one of the most active areas of cognitive science research is the study of language. Linguists study how people use grammar and how people produce and understand language. Neuroscience- neuroscientists study physiological processes involved in cognititon, at levels ranging from single nerve cells to large areas of the brain Philosophy- philosphers are concerned with problems such as whether machines that can simulate human cognitions such as perceiving, thinking, or language can have experiences like those that Chapter Summary The complexity of cognition becomes apparent when we consider questions like “Why do we take in little information about a person we are not paying attention to, even though we can easily see them?” or “Why do memories suddenly reappear when we return to a specific location?” The work of Donders (simple vs. choice reaction time), Helmholtz (unconscious inference), and Ebbinghaus (the forgetting curve for nonsense syllables) are examples of cognitive psychology from the 19th century. Because the operation of the mind cannot be observed directly, its operation must be inferred from what we can measure, such as behavior or physiological responding. This is one of the basic principles of cognitive psychology. The first laboratory of scientific psychology , founded by Wundt in 1879, was concerned largely with studying the mind. Structuralism was the dominant theoretical approach of this laboratory, and analytic introspection was one of the major methods used to collect data. In the first decades of the 20th century, behaviorism was founded by John Watson, partly in reaction to structuralism and the method of analytic introspection. Its central tenet was that psychology was properly studied by measuring observable behavior, and that invisible mental processes were not valid topics for the study of psychology. Beginning in the 1930s and 40s, B.F. Skinner’s work on operant conditioning assured that behaviorism would be the dominant force in psychology through the 1950s. In the 1950s, a number of events occurred that led to what has been called the cognitive revolution – a decline in the influence of behaviorism and the reemergence of the study of the mind. These events included the following: a. Chomsky’s critique of Skinner’s book Verbal Behavior; b. reports by Breland and Breland that biological influences made it difficult to train some behaviors using operant conditioning; c. the introduction of the digital computer and the idea that the mind processes information in stages, d. Cherry’s attention experiments and Broadbent’s introduction of flow diagrams to depict the processes involved in attention; e. interdisciplinary conferences at MIT and Dartmouth in 1956. Modern cognitive psychologists study the mind by using both behavioral and physiological approaches, which results in a more complete understanding of how the mind operates than using either one alone. Two modern examples of the behavioral and physiological approaches are Shepard and Metzler’s experiments studying the mental rotation (behavioral approach) and Divachi and coworkers’ experiment on the relationship between brain activity and memory (physiological approach.) Models play an essential role in cognitive psychology, by helping organize data from many experiments. The modal model of memory is an example of a particularly influential model. It is important to realize that models such as this one are constantly being revised in response to new data, and also that the boxes in these models often do not correspond with the brain. Cognitive science, the interdisciplinary study of the mind, includes researchers and theorists from psychology, computer science, anthropology, linguistics, neuroscience, and philosophy. Chapter 3: Perception pgs. 55-61 perception- conscious experience that results from stimulation of the senses humans are much better at perceiving objects than computers since humans use perceptual intelligence – knowledge gained from experience in perceiving (the knowledge that we bring to a situation plays an important role in perception) the process of perception (how does perception depend on incoming stimulation and existing knowledge?) perceiving objects (how are objects analyzed into features early in the process of perception? how are elements in a scene organized into objects?) perceptual intelligence (how do humans use perceptual intelligence to perceive objects? Bottom-Up and Top-Down Processing in Perception perception is a result of a complex process BEHAVIOR is determined by both the ENERGY reaching a person’s receptors and by the knowledge a person brings to a situation bottom-up processing- processing that begins with the stimulation of receptors (also called data-based processing ex: light reflected from a moth creates an image in Ellen’s eyes top-down processing- processing that involves a person’s knowledge or expectations. (also called knowledge-based processing) ex: Ellen brings her knowledge of moths to the table so that she can identify the object as a moth, not a butterfly, and identify what kind of moth it is ( so, bottom-up and top-down processing collaborate to result in perception rat-man demonstration- demonstration in which a presentation of a “ratlike” or “manlike” stimulus picture can bias perception of another picture that is presented immediately afterward, so that it is more likely to be perceived as a rat or a man. this is an example of PRIMING. this shows how recently acquired knowledge (“that pattern is a rat”) can influence perception there are numerous situations in which incoming data interacts with a person’s knowledge Chapter 2 Book Notes: Cognition and the Brain: Basic Principles Hearing and turning off an alarm clock is a seemingly simple behavior that actually involves a complex series of psychological events. sound waves are changed to electrical signals in the ear and are sent to the brain signals reaching the auditory areas of the brain cause Juan to hear the alarm signals sent from the autditory areas to the motor area cause signals to be sent from the motor area to muscles in Juan’s arm and hand so he can turn off the alarm Neurons: The Building Blocks of the Nervous System 1. Neurons, the basic units of the nervous system, both generate and transmit electrical signals. Signals are generated in neurons containing receptors by a process called transduction. The resulting electrical signals represent properties of the environment. Neurons Transform Environmental Energy into Electrical Energy neurons- cells that are specialized to receive and transmit information in the nervous system cell body- contains mechanisms to keep the cell alive dendrites- structures that branch from the cell body and receive signals from other neurons axon (nerve fiber) a tube filled with fluid that conducts electrical signals; transmits signals from the cell body to the synapse at the end of the cell body sensory receptors- specialized neural structures that respond to environmental stimuli such as light, mechanical stimulation, or chemical stimuli; for some neurons, they replace the cell body and dendrites at the receiving end these receptors respond to light energy (vision), mechanical deformation (touch, pain), pressure changes in the air (to create hearing), molecules in the air (smell), and molecules in liquid (taste). transduction- transformation of one form of energy into another. In the nervous system, environmental energy is transformed into electrical energy. ex: when you touch the “withdrawal” button on the ATM, the pressure exerted by your finger (mechanical energy) is transduced by the ATM into electrical energy, which is then transduced back into mechanical energy to operate the mechanism that pushes your money out light enters the eye through the pupil, which then activates receptors in the retina– a network of neurons that line the back of the eye; these electrical signals exit the back of the eye in one million axons that make up the optic nerve 2. Signals are recorded from single nurons using microelectrodes. This recording reveals propagated action potentials that remain the same size but increase their rate of firing in response to increases in stimulus intensity. action potentials- electrical potential that travels down a neuron’s axis these actions potentials are recorded by using tiny wires called microelectrodes that are placed in or near and axon and that pick up the electrical signals that travel down the axon The RATE at which action potentials are fired increases the stimulus intensity, but the SIZE of the action potential doesn’t matter ( so, stimulus intensity is represented not by the SIZE of action potentials but by their RATE OF FIRING!!!!!!!!!!!!! the firing if an axon causes the inside to be more POSITIVE for a millesecond, then it goes back to normal level Action potentials are propagated ( once a signal is generated at one end of the axon it travels to the other end without decreasing in size propagated= a property of action potentials. Once they are generated, they travel unchanged down the length of an axon. Presenting light causes an increase in firing of action potentials’ the more How Neurons Communicate synapse- the space between the end of an axon and the cell body or dendrite of the next axon Action potentials do not themselves travel across the synapse. Instead, they trigger a chemical process that bridges the gap between neurons. When the potentials reach the end of one neuron, they cause structures called SYNAPTIC VESICLES to open and release chemicals called NEUROTRANSMITTERS onto the next neuron neurotransmitters= chemical that is released into the synapse in response to incoming action potentials; can affect the electrical signal of the neuron that receives the neurotransmitter Excitation and Inhibition Interact at the Synapse 3. Neurons communicate with each other by their release of excitatory and inhibitory neurotransmitters at the synapse. Neural processing, which is caused by the interaction between inhibition and excitation in the neural circuits, results in individual neurons that respond to specific stimuli such as small spots, oriented lines, geometrical objects, faces, and common objects in the environment. The release of an excitatory neurotransmitter from one of the neurons increasese the chances that the next neuron will fire; this excitatory neurotransmitter is generally associated with INCREASED NERVE FIRING The release of an inhibitory neurotransmitter decreases the chances that a neuron will fire, and is therefore associated with decreased nerve firing. Thus, some neurotransmitters cause excitation (increases the rate of nerve firing) and some neurotransmitters cause inhibition (decreases the rate of nerve firing) How Neurons Process Information The brain contains 180 billion neurons, 80 billion which are involved in cognitive processes - Neurons Process Information by INTERACTING with each other Neural Processing- interactions between neurons that cause a target neuron or group of neurons to respond to specific stimuli Neural processing occurs when a number of neuropse synapse together to form a neural circuit—a group of interconnected neurons Two basic properties of these neural circuits that contribute to neural processing are: convergence – a number of neurons sending signals to a single neuron interaction of excitation and inhibition as we increase the length of the stimulus, neuron B’s firing rate increases; this occurs because stimulating more receptors increases the amount of excitatory transmitters released on the neurons. so in this circuit, CONVERGENCE is the main mechanism of neural processing since the number of neurons sending signals to a single neuron is what matters (see fig 2.8) Neural Processing Creates Neurons That Respond to Specific Types of Stimuli initially, a neuron’s response increases as the spot of light increases, but the response decreases once the spot gets too large. This result—firing best to small spots of light—is similar to the result we obtained in our hypothetical circuit Why does the small spot involve such a large increase in firing> BECAUSE when the spot is small, mainly excitatory synapses are involved. Increasing the size of the stimulus slightly involves more excitatory synapses, so firing rate increases. However, it decreases when it becomes too large Simple cells= a type of neuron in the visual cortex that responds best to presentation of an oriented bar of light Complex cells= a type of neuron in the visual cortex that responds best to a moving, oriented bar of light. Responding often occurs to a specific direction of movement. end-stopped cells= a type of neuron in the visual cortex that responds best to an oriented bar of light of a particular length moving in a particular direction ---( these cells (simple, complex, and end-stopped) that fire in response to specific features of stimuli are called feature detectors The environment is represented in the nervous system by a neural code. Specificity coding—neurons that respond selectively to only one stimulus—is possible, but the most likely type of coding is distributed coding, in which properties of the environment are represented by the pattern of firing of groups of neurons. How Stimuli Are Represented by the Firing of Neurons neural code- the representation of specific stimuli or experiences by the firing of neurons Neurons have been found in the TEMPORAL CORTEX that respond to a. complex geometrical figures, b. common objects in the environment, and c. faces The Neural Code for Perceiving faces One possible way that faces could be represented is by specificity coding- the representation of a specific stimulus, like a specific person’s face, by the firing of very specifically tuned neurons that are specialized to respond just to a specific face ex: Bill’s facewould be signaled by the firing of neuron 1 (which responds only to his face), Sam’s face- neuron 2, and Roger’s face by the firing of neuron 3 grandmother cell- a neuron that responds only to a highly specific stimulus. The stimulus could be a specific image, such as a picture of a person’s grandmother, or a concept, such as the idea of grandmothers in general, or a person’s actual g-ma. Problems with this idea: there are too many different faces and objects in in environment to assign specific neurons to each one although there are neurons that respond only to specific types of stimuli, like faces, even these neurons respond to a different number of faces each face is represented by a pattern of firing across a number of neurons distributed coding- representation of an object or experience by the firing of a number of neurons thus, each face is represented by a pattern of firing across a number of neurons advantages: firing just a few neurons can signal a large number of stimuli Cognitive Processes and the Brain 5. The brain is organized into lobes and subcortical structures. Recordings from single neurons in animals and neuropsychological research in humans have shown that these areas have specialized functions. Layout of the Brain: cerebral cortex: the 3mm thick outer layer of the brain that contains the mechanisms responsible for higher mental functions such as perception, language, thinking, & problem solving The cerebral cortex is divided into 4 lobes: temporal lobe- important for language, memory, hearing, and perceiving forms occipital lobe- the first place in the cerebral cortex where visual information is received parietal lobe- where signals are received from the TOUCH system and which is also important for vision and attention frontal lobe- serves higher functions such as language, thought, memory, and motor functioning subcortical structures- brain structures located beneath the cerebral cortex. subcortical structures that are important for cognition include the amygdale, hippocampus, and thalamus hippocampus- important for forming MEMORIES amygdala- important for emotions and emotional memories thalamus- important for processing information from the senses of vision, hearing, and touch Different Areas of the Brain Serve Specific Functions localization of function- location of specific functions in specific areas of the brain. For example, areas have been identified that are specialized to process information involved in the perception of movement, form, speech, and different aspects of memory. One area in the temporal love, called the fusiform face area (FFA), is rich in neurons that respond best to faces. Research of effects on brain damage provides evidence for localization of function. neuropsychology- the study of the behavior of humans with brain damage The basic idea behind neuropsychology is that cognitive functioning breaks down in specific ways when specific areas of the brain are damaged. The major method of neuropsych. is the determination of dissociations - situations in which one function is absent while another function is present. There are 3 types: single dissocations- which can be studied in a single person, and double dissociations- which require 2 or more people The technique of brain imaging – PET scans and fMRI scans—has made it possible to determine the activity of the brain as a person carries out cognitive task. One finding is that most cognitive tasks activate many different areas of the brain. Brain Imaging brain imaging- techniques such as functional magnetic resonance imaging (fMRI) and positron emission tomography (PET) that result in images of the brain that represent brain activity. In cognitive psychology, activity is measured in response to specific cognitive tasks. PET- positron emission tomography; a brain-imaging technique involving the injection of a radioactive tracer to measure BLOOD FLOW (since blood flow increases in areas of the brain that are activated) subtraction technique- the technique used in brain imaging in which baseline activity is subtracted for the activity generated by a specific task. The result is the activity due only to the task that is being studied. fMRI- functional magnetic resonance imaging; also based on measurement of bloodflow where blood flow is measured WITHOUT radioactive tracers ***Cognitive processes usually involve activity that is distributed throughout a number of different areas of the brain. Basically, the different parts of the brain WORK TOGETHER (like an orchestra!) Interacting With the Environment Affects Operation of the Nervous System Experiments on both animals and humans have demonstrated the property of experience-dependent plasticity, which causes neurons to become tuned to respond best to stimuli that are commonly found in the environment. The brain is able to CHANGE and adapt to its environment experience-dependent plasticity- a mechanism that causes neurons to develop so they respond best to the type of stimulation that they experience; basically, your neurons can become “tuned” to operate best within a certain environment ex: cats exposed to vertical lines develop neurons that respond best to verticals Are there grandmother cells after all? Recent research has discovered neurons in the hippocampus that respond best to concepts such as Halle Berry or the Sydney Opera House. These neurons appear to be associated with higher-order processes such as memory. COURSEPACK READINGS Dissociation of Pathways for Object and Spatial Bision: A PET Study in Humans Overview: a PET (positron emission tomography) study was conducted to determine which brain regions are differentially involved in visual object identification and object localization subjects engaged in a spatial task in which they matched the location of common objects, and an object task in which they matched the identity of common objects Right side region in parietal lobe was more activated during spatial than during object matching Introduction there is evidence suggesting that the identification of faces and common objects is carried out by at least partially distinct subsystems of the visual cortex this PET study addressed the issue directly by comparing brain activity associated with a spatial task in which subjects matched the location of line drawings of common objects, and an object task in which they matched their identity Materials & Methods 2 different tasks: an object matching task and a spatial matching task Results results provide direct evidence in support of the dual pathway model of vision in humans a dorsal region in the right-sided inferior parietal lobe was more activated during SPATIAL matching than object matching whereas bilateral ventral occipitotemporal regions were more activated, especially on the left side, during object matching than spatial matching Conclusion Ungerleider and Mishin’s dual pathway model of vision in humans extends previous findings in that they show that this model also holds for visual object identification and object localization when common objects rather than faces are processed. results demonstrate that the pattern of lateralization may vary in the ventral pathway depending on what type of spatial processing is required Visual Representation of Object Location: Insight From Localization Impairments when the visual areas of the brain are damaged or fail to develop normally, the most basic and seemingly trivial aspects of visual perception may be impaired drastically focuses on a woman with an impairment in localizing objects The Nature of the Impairment A.H.’s localization deficit was selective to vision (she could localize sound fine) basically, she could not identify if something was the right or left of a computer screen her visual deficit was present throughout her schooling Selectivity Within Vision Identification vs. Localization AH was able to recognize objects even when she mislocalized them ****this shows that LOCATION and IDENTITY are processed separately in the visual system Components of Location Representations basically, she mixed up left and right; so her errors in reaching for an object placed her left or right virtually always involved reaching to the corresponding position on the opposite side of the midline Effects of Stimulus Conditions her localization was impaired for some conditions, but was nearly intact for others her performance was very impaired for stationary, steadily illuminated, long duration stimuli, but was dramatically better for moving, flickering, or very brief stimuli Functioning in Daily Life she has difficulty with written numbers because she does not always perceive the digits in the correct order (ex: she sees “25” as “52” or “bread” as “beard”) sometimes pours water in floor instead of in plant Comparison with Previously Described Visual Localization Deficits AH’s impairment is developmental (no injuries or damage) AH’s localization errors reflect across a vertical axis, while others don’t Conclusion Despite the immediacy of visual experience, vision does not place people in direct contact with the external world. When people look around, the objects of their awareness are not things in the world, but rather representations of those things constructed by their visual systems. If the representations are inaccurate in capturing properties like location, orientation, form, or motion, people quite literally see a visual scene different from the one that is actually before them. The Man Who Mistook His Wife for a Hat Dr. P could not see faces; he couldn’t recognize people and mistook water hydrants and parking meters for children he heavily relied and his hearing to communicate with people he mistook his foot for his shoe when looking at a picture, he could not see the scene as a whole, but instead saw only the details he thought his wife’s head was a hat!!! doctor needed to see what was going on in his PARIETAL and OCCIPITAL lobes he could see cartoons, cards, etc. but he couldn’t see things in real life he didn’t recognize anyone!! not even his family after watching a movie, he could remember the plot, incidents, words of the characters, however, he omitted any visual characteristics and visual narrative or scenes. he sings all the time!! Postscript another case was similar where a man couldn’t identify his family members and could barely recognize himself in the mirror Essentials of Clinical Neuroanatomy and Neurophysiology see pictures Chapter 3: pgs. 61-2 & 69-90 Recognizing Letters & Objects template matching- a model of object recognition that proposes that recognition occurs when a stimulus matches a specific template but, this model won’t work because then there would have to be a huge number of different templates just to recognize one letter (because letters are often at angles) Interactive Activation Model- proposes that activation is sent through 3 levels: feature level- contains feature units; responds to specific features such as straight lines, curved lines, or lines with a specific orientation letter level- contains letter units, which responds to specific levels word levels- contains word units; recognizes and responds to specific words ex: recognizing single letter ( recognizing single word ( recognizing a letter within a word Recognition-by-Components Theory recognition by components theory (RBC)- a feature-based approach to object perception that proposes that the recognition of objects is based on 3-dimensional features called geons basic message: if enough information is available to us to identify an object’s basic geons, we will be able to identify the object geons- basic feature unit of recognition by components theory; there are 36 different geons geons can be identified and viewed from different angles view invariance- in recognition-by-components theory, the idea that geons can be identified and viewed from many different angles ex: picking up a book and viewing it at many different viewpoints Two other properties of geons: discriminability- each geon can be distinguished from others from almost all viewpoints resistance to visual noise- we can still perceive geons under “noisy” conditions (lex: low light or fog) Perceptual Organization: Putting Together an Organized World perceptual organization- the organization of elements of the environment into objects Gestalt psychologists- disagreed with structuralist approach to perception; proposed the laws of perceptual organizationj and were concerned with how figure is separated from ground structuralism- adding up small, elementary units called sensations the Gestalt psychologists are different since they consider the overall pattern The Gestalt Laws of Perceptual Organization- a series of rules that specify how we perceptually organize parts into wholes The 6 Laws: Law of Pragnanz- central law of Gestalt psychology (also called law of good figure or law of simplicity): every stimulus pattern is seen in such a way that the resulting structure is as simple as possible ex: the Olympic rings Law of Similarity- Similar things appear to be grouped together includes similarity of lightness, hue, size, or orientation Law of Good Continuation- points that, when connected, result in straight or smoothly curving lines, are seen as belonging together, and the lines tend to be seen as following the smoothest path Law of Proximity or Nearness: things that are near each other appear to be grouped together Law of Common Fate: things that are moving in the same direction appear to be grouped together ex: flock of birds seem to be moving as a unit Law of Familiarity: things are more likely to form groups if the groups appear familiar or meaningful In a nutshell: The Gestalt approach to perception proposes laws of organization to explain how we perceptually organize parts into wholes. Because these laws provide “best guess” predictions of what is out there, they can be called heuristics. The Gestalt heuristics are just one example of the way our perceptual system is designed to deal with our environment. The Gestalt Laws Provide “Best Guess” Predictions About What is Out There the Gestalt laws help provide accurate information because they reflect things we know from long experience in our environment and because we are using them unconsciously all the time the Gestalt laws usually result in accurate perceptions of the environment,m but not always heuristic: rule of thumb that provides a best-guess solution to a problem; not always correct algorithm: a procedure guaranteed to solve a problem ex: addition, subtraction, division, etc Why Computers Have Trouble Perceiving Objects A Stimulus on the Receptor is Ambiguous inverse projection problem- the ambiguity of the retinal image caused by the fact that a particular image could be caused b y an infinite number of objects with different sizes, shapes, orientations, and located at different distances from the eye. Objects Need to be Distinguished From their Surroundings and From Each Other speech segmentation- the organization of speech into individual words Objects Can be Hidden or Blurred The Reasons for Changes in Lightness & Darkness Can Be Unclear Humans have PERCEPTUAL INTELLIGENCE- since we perceive by using both the information that stimulates the receptors and the knowledge that we bring to a situation How Experience & Knowledge Create Perceptual Intelligence Heuristics for Perceiving Gestalt laws of organization are most accurately described as heuristics Occlusion heuristic- when a large object is partially covered by a smaller object, we see the larger one as continuing behind the smaller occluder ex: people leaning against railing light-from-above heuristic- assumption that light is coming from above Knowledge Helps Us Perceive Words in Conversational Speech “I scream” vs. “ice cream” “big girl” vs. “Big Earl” transitional probabilities- the chances that one sound will follow another sound statistical learning- the process of learning about transitional probabilities and about other characteristics of learning It has been difficult to develop computer programs for perceiving objects because the stimulus on the receptor is ambiguous, objects need to be distinguished from their surroundings and from each other, objects can be hidden or blurred, and the reasons for changes in lightness and darkness can be unclear Humans solve the problems that are difficult for computers because humans possess built-in knowledge, which we can call PERCEPTUAL INTELLIGENCE. Examples of this knowledge are heuristics for perception, such as the Gestalt laws and other heuristics that reflect characteristics of the environment, and knowledge of word meanings and transitional probabilities between sounds that helps us achieve speech segmentation. Chapter 3: pgs. 62-66 Pattern Recognition: Top Down Processing Interactive Activation Model- McLelland and Rumelhart’s model or word recognition that proposes that word recognition is based on activation sent through three levels: Feature Level- contains feature units; units receive inputs from stimuli in the environment and respond to specific features such as straight lines, curved lines, or lines with specific orientation Letter Level- contains letter units, which respond to specific letters; letter units receive inputs from feature units Word Level- contains word units, which are all of the words that a person knows; receives input from letter units Feature Level: I / \ Letter Level: L M F Word level: Fork Roof Recognizing a Single letter: K= one straight line and two slanted lines Recognizing word: FORK= F O R K The Word Superiority Effect: letters are easier to recognize when they are contained in a word, compared to when they appear alone or are contained in a nonword ex: the K in FORK makes more sense than the K in RFOK ( the word superiority effect shows that letters in words are not processed letter by letter, but each letter is affected by its surroundings Recognizing a Letter Within A Word: feedback activation: in interactive activation model of word recognition, activation that is sent from word units back to each of the letter units for that word ex: FORK - - - - - > F so, the letter F and each of the other letters in FORK are more highly activated when they appear in the word than when they appear alone or in a nonword SEE MODEL on PAGE 66!!! This model takes TOP DOWN processing into account: bottom up processing is initiated by stimulation of the receptors, and top-down processing occurs when a person’s knowledge affects processing Thus, in this model, bottom up processing occurs when letter or word stimuli activate the receptors, which then activate feature units. Top-down processing is also involved because the existence of word units is based on the person’s knowledgeof which strings of letters form words, and the feedback activation that is sent back from the words to the letter units reflects top-down processing. word units ( - - -> letter units ( feature units ( top-down processing bottom-up processing Above: this is a summary of how activation flows in the interactive activation model. Activation flowing from the feature units toward the word units represents bottom-up processing. Activation flowing from the word units to the letter units represents top-down processing. Chapter 3: pgs. 66-69 Feature Integration Theory (FIT)- an approach that proposes that object perception occurs in a sequence of stages in which features are first analyzed and then combined to result in perception of an object First stage of perception is the preattentive stage- the first stage, where an object is analyzed into its features The second stage is called the focused attention stage- where the features are combined so that we can perceive the object Flow Diagram for Treisman’s feature integration theory: object ( Preattentive stage (analyze into features) ( focused attention stage (combine features) ( perception illusory conjunctions- a situation where features from different objects are inappropriately combined Feature Integration Theory (FIT)- at the beginning of the process, perceptions of each of these components exist independently of one another, just as the individual letter tiles in a game of Scrabble exist as individual units when the tiles are scattered at the beginning of the game. However, just as the individual Scrabble tiles combine to form words, these individual features combine to form perceptions of whole objects. Balint’s Syndrome- a condition caused by brain damage that makes someone unable to focus attention on individual objects Illusory conjunctions are LESS likely to occur when a person is expected to be shown a certain object; ex: they think a triangle is orange if they expect a “carrot” ( this is TOP-DOWN processing **Feature integration theory describes rapid processes that occur at the beginning of object perception, in which objects are broken down into features, and then these features create the perception of objects. Chapter 4: Attention Attention- concentrating on specific features of the environment, or on certain thoughts or activities ( we focus on some things to the exclusion of others Attention has an effect on perception, on memory, on language, and on problem solving. Selective Attention- the ability to focus on one message and ignore all others Dichotic listening- procedure of presenting one message in the left ear and one message in the right ear shadowing- the procedure of repeating a message out loud as it is heard; goal is to ensure that participants are focusing their attention on the attended message Cocktail party phenomenon- the ability to pay attention to one message and ignore all other messages—because it resembles what people routinely achieve in a noisy party when they focus on one message and ignore all others Broadbent’s Filter Model of Attention (Broadbent)- model that proposes that selective attention is achieved by filtering out unattended messages Sensory memory, which holds all of the incoming information for a fraction of a second then transfers it on to the next stage The filter identifies the attended message based on its physical characteristics—things like the speaker’s tone of voice, pitch, speed of talking, and accent—and lets only this message pass through to the detector in the next stage. All other messages are filtered out. The detector processes information to determine higher-level characteristics of the message such as its meaning. Because only the important, attended information has been let through the filter, the detector processes all of the information that enters it Short-term memory receives the output of the detector. Short-term memory holds information for 10-15 seconds and also transfers information into the long term memory Messages ( Sensory Memory ( Filter ( (attended message) ( Detector ( To memory Broadbent’s model is called an early-selection model- the model of attention that explains selective attention by early-filtering out of the unattended message. The filtering occurs before the information is analyzed to determine its meaning ex: think of a sand filter (sieve) at the beach A number of models have been proposed to explain the process of selective attention. Broadbent’s filter model proposes that the attended message is separated from the incoming signal early in the analysis of the signal. Treisman’s model proposes later separation and adds a dictionary unit to explain how unattended messages can sometimes get through. Late selection models propose that selection doesn’t occur until messages are processed enough to determine their meaning. Treisman’s Attenuation Theory of Attention- proposes that selection occurs in 2 stages: an attenuator analyses the incoming message in terms of 1. its physical characteristics (whether it is high pitched or low pitched, fast or slow) 2. its language, and 3. its meaning Attended messages pass through the attenuator at full strength and unattended messages pass through with reduced strength message is analyzed by the dictionary unit- processing unit that contains stored words and thresholds for activating units. This unit helps explain how we can sometimes hear familiar words (our name) in an unattended message Messages (< Attenuator --> (attended & unattended messages) ( dictionary unit ( to memory Basically, Treisman’s model is similar to Broadbents, but different in the fact that Language and Meaning can also be used to separate the models. Treisman proposes that the analysis of the message proceeds only as far as is necessary to identify the attended message ex: if there are 2 messages, one male and one female voice, then analysis at a physical level is adequate to separate. However, if the voices are similar, then it may be necessary to use the message’s meaning to separate the two messages According to Treisman, words that are common or especially important (one’s name), have low thresholds, so even a weak signal in the unattended channel can activate that word, and we hear our name from across the room. Uncommon words or unimportant words have HIGHER thresholds, so it takes the strong signal of the attended message to activate these words. Thus, according to Treisman, the attended message gets through, plus some parts of the weaker unattended message. Treisman and Broadbent’s models are both considered to be EARLY-SELECTION models since attended and unattended messages are separated early in the information processing system. However, because further selection can also occur later, we have called Treisman’s model an intermediate-selection model. Late-Selection models- state that selection of stimuli for final processing doesn’t occur until after the information has been analyzed for its meaning. (McCay) task load- how much of a person’s cognitive resources are used to accomplish a task. The idea of task load is important for some explanations of selective attention and also for explanations of how people process information in working memory. A difference between the early and late selection approaches to selective attention is the characteristics of the messages that are used to accomplish selection. Early selection (Broadbent’s approach) is based on physical characteristics. Late selection (MacKay’s approach) is based on meaning. Treisman’s attenuation model falls in-between these two because selection can be based on physical characteristics, meaning, or both. How does task load affect selective attention? high load tasks- tasks that use most or all of a person’s resources and so leaves no capacity to handle other tasks low load tasks- tasks that use few resources and leave some to handle other tasks high load- studying for a final exam vs. low load- paging through a magazine while on the elliptical Flanker-Compatability Task- a procedure in which participants are instructed to respond to a target stimulus that is flanked, or surrounded, by distracter stimuli that they are supposed to ignore. The degree to which the distracter interferes with responding to the target is taken as an indication of whether the distracter stimuli are being processed. - the type of distractor can affect the detection of the target (compatible [same] vs. incompatible [different] distractor) When the task laod is high, the type of distractor does not affect reaction time. This occurs because the participant needs to use all of his or her resources to deal with the more complex display, so there are no resources left to process the distracter. ***Playing video games can enhance the ability to process visual information The ability to selectively attend is affected by task load. Flanker-compatibility experiments have shows that when attentional tasks involve low load, some cognition capacity remains, so some processing of unattended signals can occur. When attentional tasks involve a high load, processing of unattended material is prevented. Lavie suggests that the results of experiments supporting early and late selection can be explained in terms of the effect of task load. Divided Attention: Paying attention to more than one thing divided attention- the ability to pay attention to two or more tasks simultaneously Practice can make it possible for participants to divide their attention to deal with all of the target and test items simultaneously automatic processing- a type of processing that occurs a. without intention (it automatically happens without the person intending to do it), and b. at a cost of only some of a person’s cognitive resources ex: listening to audiobooks while sorting male Stroop Effect- specifying the color of the ink, and not the na,e spelled out Automatic Processing Is Not Possible for Difficult Tasks controlled processing- processing that involves paying close attention SUMMARY: Divided attention is possible if tasks are easy or well-practiced. Divided attention becomes difficult or impossible, however, when even one of the tasks becomes too hard. For example, it’s easy to talk and drive at the same time if you are on a familiar road. But, if there’s a lot of construction and traffic, you may have to just focus on driving Divided Attention in the Real World: Inattention and Driving Hands-free cell phones offer NO safety advantage **Results of experiments using the flanker-compatibility task show that video-game players are not as affected by high task load as nonplayers **Divided attention is possible for easy tasks, or for highly practiced difficult tasks. In these situations, automatic processing is possible. Divided attention is not, however, possible for highly demanding tasks, which require controlled processing. **Driver inattention is one of the major causes of automobile accidents. There is evidence that using cell phones while driving decreases driving performance and causes accidents. Attention & Visual Processing Directing Visual attention with the eyes saccades- rapid movements of the eyes from one place to another fixations- short pauses on points of interest; we make an average of 3 fixations per second when viewing a scene eye tracker- a device that measures where people fixate when looking at a scene and how their eyes move from one fixation point to another stimulus salience- bottom up factors that determine attention to elements of a scene. Examples are color, contrast, and orientation. The meaningfulness of the images (which is a top-down factor), does NOT contribute to stimulus salience we are more likely to focus on HIGHLY SALIENT areas (bright color, contrast, orientation) ( stimulus salience is solely triggered by bottom-up processing scene schema- a person’s knowledge about what is likely to be contained in a particular scene. This knowledge can guide people’s attention to different parts of a scene. ex: people’s knowledge of a desk may influence person to look at the desk when looking for a computer ex: books usually are in a bookcase, etc. when carrying out a task, the demands of the task override factors such as stimulus saliency Key findings: a person’s eye movements are determined primarily by the TASK Directing Visual Attention Without Eye Movements we can look directly at something without paying attention to it; OR, we can not look directly at something and pay attention to it Inattentional Blindness- not noticing something even though it is in clear view, usually caused by failure to pay attention to something es: when you’re looking at a sentence but it doesn’t register precueing- a procedure where participants are given a cue which usually helps them out with their task; this cue tells them where to direct their attention in a visual experiment ---- paying attention off to the side can affect information processing at the plaace where attention is directed Object-Based visual attention location-based attention- models of attention that propose that attention operates on whatever stimuli are at a particular location. this contrasts object-based attention, which says that attention is associated with specific objects object-based attention- enhancing effects of intention occur when looking at a specific OBjECT Attention can be based both on where a person is looking in the environment(location-based) and on where a person is looking on a specific object (object-based). these both operate under different conditions location-based and object-based attention activate DIFFERENT parts of the brain Attention in Social Situations—The Cause of Autism Attention is a crucial component of social situations; we pay attention to what others say and their facial expressions, body language, etc. even though people with autism can solve reasoning problems, they are awkward in social situations autistic observers tend to direct their attention to the place where a person is pointing **Eye movements are a basic mechanism for determining attention to different parts of a visual scene. Both bottom-up processes, like stimulus salience, and top-down processes, such as scene schemas, influence how eye movements are directed to parts of a scene. **Visual attention can be directed to different places in a scene even without eye movements. This has been demonstrated by precueing experiments, which have shownt hat paying attention to a location enhances processing at that location (LOCATION-BASED ATTENTION) ** Object-based attention= attention directed toward specific object. enhancing effects of attention are spread throughout an object. **People with autism do not direct their attention in social situations in the same way as nonautistic observers. Autistic people attend to things, whereas nonautistic people attend more to other people. Chapter 9: Visual Imagery Mental imagery- experiencing a sensory impression in the absence of sensory input Visual imagery- a type of mental imagery involving vision, in which an image is experienced in the absence of a visual stimulus “seeing” in the absence of a visual stimulus The Uses of Visual Imagery: - visual imagery provides a way of thinking that adds another dimension to purely verbal techniques Mental imagery is experiencing a sensory impression in the absence of a sensory input. Visual imagery is “seeing” in the absence of a visual stimulus. Imagery has played an important role in the creative process and as a way of thinking, in addition to purely verbal techniques Early Ideas About Imagery: imageless-thought debate- the debate about whether thought is possible without an image Imagery & the Cognitive Revolution: Paired-associate learning- learning that occurs when a participant is presented with a pair of words during a study period and then is tested when one of the words is presented and the task is to recall the other world ex: boat-hat or car-house Conceptual-peg hypothesis- a hypothesis associated with Pavio’s dual coding theory stating that states that concrete nouns create images that other words can hang on to, and that this enhances the memory for these words ex: hotel-student vs. knowledge-honor (concrete nouns like hotel & student are much easier to “hang onto” than abstract nouns like knowledge and honor) Early ideas about imagery included the imageless-thought debate and Galton’s work with visual images, but imagery research stopped during the behaviorist era. Imagery research began again in the 1960’s, with the advent of the cognitive revolution. Imagery & Perception: Do they share the same mechanisms? mental scanning- a process of mental imagery in which a person scans a mental image in his or her mind Kosslyn’s Mental Scanning Experiments- In one experiment, Kosslyn asked participants to memorize a picture of a BOAT and then create an image of that object in their mind and then focus on one part of the boat, such as the anchor. They were then asked to look for another part of the boat, such as the motor, and to press “True” when they found this part or “false” if they couldn’t find it Kosslyn reasoned that if imagery, like perception, is spatial, then it should take longer for the participants to find parts located farther from the initial point of focus because they would be scanning across the image of the object. imagery debate- a debate about whether imagery is based on spatial mechanisms such as those involved in perception, or is based on mechanisms related to language, which are called propositional mechanisms. The idea that imagery shares the same mechanisms as perception (that is, creates a depictive representation in the person’s mind) was suggested by Kosslyn’s mental scanning experiments, but these results and others were challenged by Pyllyshyn, who stated that imagery is based on a mechanism related to language (that is, it creates a propositional representation in the person’s mind.) The Imagery Debate: Is Imagery Spatial or Propositional Kosslyn: spatial representation- a representation in which different parts of an image can be described as corresponding to specific locations in space\ - most researchers accept the spatial representation of visual imagery Pylyshyn: believes the spatial experience of mental images is an epiphenomenon- something that accompanies the real mechanism but is not actually part of the mechanism believes that mental images indicate that something is happening in the mind, but they don’t tell us how it is happening - proposes that the mechanism underlying imagery is not spatial but is propositional ( propositional representation- a proposition in which representations are represented by symbols, as when the words of language represent objects and the relationships between objects thus, the propositional representation of a cat under the table would be the notation UNDER (CAT, TABLE) in contrast, the spatial representation would involve a spatial layout showing the cat and table ( this is called depictive representations- corresponds to spatial relationships; the spatial relationship is depicted by the picture Motor ( rear deck ( cabin ( front deck ( anchor tacit-knowledge explanation- states that participants unconsciously use knowledge about the world in making their judgments - Pylyshyn argues against the idea of a depictive representation using this tacit knowledge explanation Both the spatial and propositional approaches to imagery show how data can be interpreted in different ways. Pylyshyn’s criticisms stimulated a large number of experiments that have taught us a great deal about the nature of visual imagery. This evidence supports the idea that imagery is served by a SPATIAL mechanism. and that it shares mechanisms with perception. 4. One of Pylyshyn’s arguments against the idea of a depictive representation is the tacit-knowledge explanation, which states that when asked to imagine something, people ask themselves what it would look like to see it, and then they simulate this staged event. Comparing Imagery & Perception Kosslyn’s other experiment: looks at how imagery is affected by the size of an object in a person’s visual field Size in the Visual Field Does the relationship between viewing distance and the ability to perceive details also occur for mental images? So, Kosslyn says: Imagine an elephant and rabbit ( elephant fills visual field Imagine rabbit and fly ( rabbit fills visual field mental-walk task- a task used in imagery experiments in which individuals are to imagine they are walking toward their mental image of an object the task was to estimate how far away they were from the animal when they began to experience “overflow”—when the image filled the visual field or when its edges started becoming fuzzy. Results: participants had to move closer for smaller animals and farther for larger animals Conclusion: Therefore, images are SPATIAL (we imagine things big or small), just like perception Interactions of Imagery & Perception Another way to demonstrate connections between imagery and perception is to show that they interact with one another; basic rationale: if imagery affects perception, or perception affects imagery, this means that imagery and perception both have access to the same mechanisms Is there a way to resolve the imagery debate? Despite all the evidence, we still cannot rule out the propositional explanation difficult to rule out Pylyshyn’s tacit knowledge explanation instead of relying solely on behavioral experiments, we should investigate how the brain responds to visual imagery Fink and Pinker’s “flashed dot” experiment argued against the tacit-knowledge explanation. The following experiments also demonstrated parallels between imagery and perception: 1. size in the visual field (visual-walk task) 2. interaction between perception and imagery, and 3. physiological experiments. Imagery and the Brain There is a TON of evidence that points to a connection between imagery and perception Imagery Neurons in the Brain there are neurons that respond to some objects, but not others there are neurons that respond to specific objects, called category0specific neurons imagery neurons- a type of category-specific neurons that respond to both perceiving an object and to imagining it. Brain Imaging Both perception and imagery activate the visual cortex there is an overlap between areas activated by perceiving an object and those activated by creating a mental image of the object, however, there are also several differences too Basically, imagery and perception share some mechanisms! 6. Parallels between perception and imagery have been demonstrated physiologically by the following methods: 1. recording from single neurons (imagery neurons) 2. brain imaging (demonstrating overlapping activation in the brain) 3. transcranial magnetic stimulation experiments (comparing effect of brain inactivation on perception and imagery), and 4. neuropsychological case studies (removal of visual cortex affects image size; unilateral neglect). There is also physiological evidence for differences between IMAGERY and PERCEPTION. This evidence includes 1. differences in areas of the brain activated and 2. brain damage causing dissociations between perception and imagery. Transcranial Magnetic Stimulation: Although many brain imaging experiments are consistent with the idea that imagery and perception share the same mechanisms,. showing that an area of the brain is activated by imagery does not PROVE that this activity CAUSES imagery. According to Pylyshyn, brain activity in response to imagery may be indicating that something is happening, but may have nothing to do with causing imagery. To deal with this possibilitiy, there was an experiment done using a technique called: transcranial magnetic stimulation (TMS): a procedure in which magnetic pulses are applied to the skull in order to temporarily disrupt the functioning in a part of the brain ( Kosslyn concluded that the brain activation that occurs in response to imagery is not an epiphenomenon and that brain activity in the visual cortex plays a causal role in both perception and imagery. 8. Most psychologists, taking all of the above evidence into account, have concluded that imagery is closely related to perception and shares some (but not all) mechanisms. Neuropsychological Case Studies -using people with brain damage to help us understand imagery Removing Part of the Visual Cortex Decreases Image Size- this supports the idea that the visual cortex is important for imagery Perceptual Problems are Accompanied by Problems with Imagery people who lost the ability to see color are unable to create colors through imagery@@@ unilateral neglect- a problem caused by brain damage, usually to the right parietal lobes, in which a patient ignores the left half of their visual field ex: eating food on one side of the plate; shaving one side of face Dissociations between Imagery & Perception there have been dissociations between imagery and perception; for example. a person’s brain damage had little effect on his ability to perceive but caused neglect in his mental images another case of normal perception but impaired images is a case where the dude could not visually recognize objects but he could draw objects from memory in rich detail Making Sense of the Neuropsychological Results: The neuropsychological cases present a paradox: On one hand, there are many cases in which there are close parallels between perceptual deficits and deficits in imagery. On the other hand, there are a number of cases in which dissociations occur, so that perception is normal but imagery is poor, or vice versa. How to explain this paradox? Basically, the mechanisms for perception and imagery overlap only PARTIALLY According to this idea, visual perception involves bottom up processing, which starts when the light enters the eye and an image is focused on the retina, then continues as signals are sent along the visiual pathways to the visual cortex and then to higher visual centers. The visual cortex is crucial for perception because it is here that objects begin being analyzed into components and orientations. In contrast, imagery is a TOP-DOWN process, which originates in HIGHER brain areas that are responsible for memory. Mental images are therefore “preassembled” and do NOT depend on activation of the visual cortex CONCLUSIONS from the imagery debate: SHARED MECHANISMS for IMAGERY and PERCEPTION Imagery and perception are closely related and share some, but not all, mechanisms Using Imagery to Improve Memory Visualizing Interacting Images participants who created IMAGES based on two paired words (like BOAT and TREE) remembered over twice as many words visualization is most effective when objects are paired in an interactive way ( bizarreness has NO effect method of loci- a method in which things to be remembered are placed at different locations in a mental image of a spatial layout Associating Images with Words pegword technique- things to be rememberd associated with concrete words ex: one-bun, two-shoe, three-tree, four-door, five-hive, six-sticks, etc… 9. The action of imagery can improve memory in a number of ways: 1. visualizing interacting images 2. organization using the method of loci, 3. associating items with nouns using the pegword technique. 10. Solving problems using mechanical reasoning can be carried out using either mental simulation or rule-based approaches. Experiments with the water-pouring problem show that it is unlikely that tacit knowledge is involved in using imagery to solve this problem. Experiments with the pulley problem indicate that people direct their attention to imagining specific areas of the problem. Quiz: Ira and his sister are playing "Name that Tune." The object of the game is to name the title of the song when given the song's first line. Ira suggests the first line "Sleigh bells ring, are you listening?" His sister can't come up with the answer at first, but realizing that the title is often embedded in the lyrics, she tries to sing them silently to herself. She then bursts out "Ah! It's "Winter Wonderland." It is most likely that Ira's sister used ________ in playing the game. inner audition “Early” researchers of imagery proposed all of the following ideas: imagery is not required for thinking images are one of the three basic elements of consciousness thought is impossible without an image NOT: imagery requires a special mechanism Shepard’s and Metzler’s image rotation experiment was so influential and important to the study of cognition because it demonstrated: –imagery and perception may share the same mechanisms Which of the following has been used AGAINST the idea that imagery is spatial in nature? TACIT-KNOWLEDGE EXPLANATION= an explanation proposed to account for the results of some imagery experiments that states that participants unconsciously use knowledge about the world in making their judgments. This has been used as one of the arguments AGAINST describing imagery as a depictive or spatial representation Perk’s experiment, in which participants were asked to “project” visual images of common objects onto a screen showed that: imagery and perception can interact with one another Perception = __________ and Imagery= __________ (according to Behrmann) perception = bottom-up imagery= top-down The pegword technique relies on: rhymes visualizations associations pegword technique- a method of remembering things in which things are associated with words The mental simulation approach for solving mechanical problems is analogous to the idea that visual imagery involves ________ respresentations. spatial Coursepack Reading: Kosslyn Mental Imagery: visual mental imagery = “seeing” in the absence of the appropriate immediate sensory input Purposes & Problems: What is imagery for? - to identify properties of imaged objects, which allows us to retrieve information from memory - to retrieve information from memory in circumstances when 1. the information to be remembered has a subtle visual property, 2. the property has not yet been explicitly considered previously, 3. property cannot easily be deduced from other stored information - allows us to navigate, track, and reach; enables us to anticipate what will happen if one’s body or object moves in a certain way - people also use imagery to help produce description, etc. Problems to be solved: - in many imagery tasks we are able to maintain the image over time, and even transform the image in some way. The Human Processing System Image Generation: a. one subsystem activates visual memory representations a second subsystem is used to position individual parts of the image basically, subsystems arrange parts into images Image Inspection objects seem to be “inspected” in imagery in the same way that they are in actual perception unilateral visual neglect= when a person ignores objects on one side of their visual field recognition mechanisms are used in imagery—people who could not recognize faces perceptually could not interpret faces in imagery Image Maintenance: we can retain relatively little information in an image at once the critical measure is the number of chunks, the number of perceptual units that are present Image Transformation we can mentally rotate objects imagined objects can be expanded or reduced in size Individual Differences there are always individual differences in imagery What is a mental image? we experience mental images as fleeting, ethereal entities - the content of a representation is the specific information conveyed Propositional Representations ball sitting on a box = ON (BALL, BOX) Syntax: Semantics- the meaning of individual symbols is arbitrarily assigned Depictive Representations: no explicit symbol that stands for the relationship depictions are VISUAL The Imagery Debate Pylyshyn’s critique of mental imagery focused on arguments that the very idea of mental imagery is paradoxical (who looks at the images?) or muddled (In what ways are images like pictures?) Scanning Visual Mental Images depictions embody space depictive representations underlie the experience of “having an image” Different Mechanisms? The First Phase of the Debate One way to discover whether image representations embody space is to determine whether it takes more time to shift attention greater distances across an imaged object; if subjects take more time to scan a longer distance across an imaged object, we would have evidence that distance is indeed embodied in the representation of the object,. Hypothesis: If image representations depict information, then it ought to take more time to locate the representations of parts located farther from the point of focus. And this is exactly what happened. BUT…. a propositional representation involves: a series of linked hierarchies of propositions, with each hierarchy describing the relations among parts of a portion of the object. Bottom-of (propeller, motor), rear-of (motor, rear, deck), and so on. propositional structures are NOT depictions Times increased LINEARLY with both difference and the amount of material scanned over ***The time to scan the image increased linearly with greater distance scanned across But….there’s always a propositional counterexplanation Demand Characteristics? The Second Phase of the Debate Two problems were raised: experimenter-expectancy effects – experimenter’s expectations influence results task demands Cognitive Neuroscience: The Third Phase of the Debate Three pieces of information were critical: it has long been known that some visual areas of the brain are topographically organized. these regions of cortex preserve the spatial structure It has been found that connections between visual areas typically do not simply send information downstream; rather, the connections run in both directions areas of the brain that store visual memories are not topographically organized

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